The southwest region is located geographically within Argyll and extends southwards towards Carradale 132kV substation. There are two 220kV subsea cables connecting the SSEN Transmission and Scottish Power Transmission (SPT) licence areas. In recent years, we have been monitoring power quality issues in this region of our network. This has manifested in voltage distortions at Crossaig Substation. The disturbances remain above the planning threshold for the system and show no trend towards resolution without physical intervention in the network.

Based on system testing, we know that installation of a harmonic filter would have an immediate impact on the fifth order harmonics observed at Crossaig substation. We therefore intend to focus further optioneering on those substations in the immediate vicinity of the Crossaig substation (at differing voltage levels) to ensure we select the most economic and effective option as our preferred option.